Alternating-current cable transmitter



May 8, 1928. 1,669,041

' A. CLAUSING ALTERNATING CURRENT CABLE TRANSMITTER Filed March 21. '1925 TIE-Z H mil nail lhll Inn lHll Hm I HH nu I!!! H! IIH my Patented May 8,. 1928.

UNITED sTATEs (PATENT. OFFICE,

ARTHUR CLAUSING, or BERLIN-CHARLOTTEN'BURG, GERMANY, AssrGNoR To sIEMEns & HALSKE, axrrnnensnusommm, or SIEMENSSTADT, NEAR BERLIN; AND ELSE- I \VI-IERE, A CORPORATIONOF GERMANY.

ALTERNATING-CURRENT CABLE TRANSMITTER.

Application filed March 21, 1925, Serial No. 17,315, and in Germany lllarc li 25i, 1924.

7 ,In the U. S. application for patent Serial No. 661,174 filed September 6, 1923, to

Luschen et al. for alternating current telegraphy,' reference is made to'the fact: that in telegraphy with alternating current over long cables the current flowing thru the cable is composed of a direct current impulse (transientcomponent or equalizing current) on which is superimposed the carrier current.

pulses whose direction continually alternates in accordance with the frequency of the current used.

If now in accordance with the explanation given in the aforesaid application a direct current component'is formed upon which the alternating current of the signal is superimposed a receiver connected in the ordinary way to the far end of the cable would not respond to thea lternating current component but since the direct current. component quite frequently has many times the amplitude of the alternating curent component it would respond to the direct current com ponent. This would mean in other words that the tolegraphing speed which is expect ed to be raised by using alternating current would again be limited to that with so-called direct current cable telegraphing.

In order to prevent this the aforesaid application proposes to insert atthe receiving end a. transformer between the cable end and the receiving apparatus proper. The impedance of the secondary winding of thistransformer is made of the order of the re So-called alternating current telegraphy 1s by no means identical with ordinary cable telegraphy 1n which latter the mary of such a transformer potentialdilierences for the alternating current arise whereas for the direct current component no appreciable potential dilierencesLcan develop.

By means of this existing alternating potential; an alternating current will be produced in the secondary of such. a transformer which can be directly used for operating the receiver. 7

I have found that it is possible to diminish the effect of the equalizing current upon the receiver by inserting a repeater at the beginning of the line behind the transmitter. An example illustrating how this is done is shown in the accompanying drawing in which Fig. 1 represents a transmitter circuit diagram and Figs. 2 and 3 represent oscillograms. The transmitter a may by means of the key t be connected to the primary windings of the repeater (transformer) u. The secondary winding of this repeater is connected to the cable is, the remote end of which is supposed to be connected to the receiver.

A considerably improved eli'ect is however obtained by employing repeaters (transformers) at the transmitting end as well as at the receiving end of the cable.

In the Figures 2 and 3 two oscillograms are shown as examples. Of these the oscillogram shown in Fig.2 has been taken when a repeater was arranged behind the sender and the oscillogram of Fig. 3 has been taken when a repeater was arranged at both ends of the telegraph line. The upper curves of each loscillogram show the original signals as delivered by the transmitter, whilst the lower curves show the signals finally observed in the receiver. As will be seen from these figures the transmitting of the signals according to Fig. 3 takes place almost completely regularly, without any elfect of the equalizing current being noticeable, whereas in Fig. 2 the elfect of the equalizing current is still rather perceptible.

What I claim as my invention and desire to secure by Letters Patent is 1. In a coupling arrangement for the transmission of telegraphic signals by means of alternating currents over cables particularly submarine cables, at source of alternating current, a signal transmitter. a cable for conveying the transmitted signals and a repeater connecting the said signal transmitter to the said cable, the primary impedance of said repeater being of the order of the apparentimpedance of the source of alternating currents and the secondary impedance of said repeater being of the order of the impedance of the cable With respect to the carrier frequency in order to transmit the maximum amount of carrier frequency energy and to attenuate the transient current impulses which tend to flow through the cable. i

2. In a coupling arrangement for the transmission of telegraphic signals by means of alternating current over cables, particularly submarine cables, a source of alternating currents, a signal transmitter, a cable, a receiver, a repeater connecting the said transmitter to said cable, and another repe'ater connecting the said receiver to the said cable, the primary impedance of the first repeater being substantially of the order of the alternating current source impedance and the secondary impedance o'lthis repeater being substantially of the order of the cable impedance, the primary impedance of the second repeater being substantially of the order of the cable impedance and the secondary impedance of this repeater being similarly matched with the receiver impedance at the carrier frequency employed in order to transmit the maximum amount of the carrier frequency energy and to attenuate the transient current impulses Which tend to flow through the cable.

In testimony whereof I afiix my signature.

ARTHUR CLAU SIN G. 

